Like others on this forum I could not get the ADC-100 to run on relatively new computers with or without the adapter. I tried the famous "patch", installing an LPT2 board, installing new versions, modifying ini files - all to no avail. Finally, the following procedure was successful on an XP machine. One must perform all steps in sequence to ensure success.

1. Uninstal the Pico software and clean the computer thoroughly, because the uninstallation leaves traces behind: (a) delete the PICO directory(s) completely; (b) delete from the win.ini file ALL lines related to PICO, which usually appear under the "[PicoScope for Windows]" title. Also remove the "[PicoScope for Windows]" title from the win.ini file.

2. Reboot

3. Instal the new version from Picotech (I used release 5.09.6)

4. Add the following lines to the win.ini file:
[ADC100]
UseAdapter=Yes